The present invention relates to a ZIF type socket, especially a ZIF type IC socket which is used for the mutual connection of an IC package such as a BGA (ball grid array) and a board.
As performance of central processing units (CPUs) has dramatically increased, there has become a widespread need in computers for easy replacement of existing CPUs with higher-speed CPUs. In such cases, zero insertion force (ZIF) type sockets are widely used as sockets for accommodating the CPU package and making mutual connections with the circuit board. Generally, ZIF type sockets have a lever which drives a slider that opens and closes an internal contact, as shown in Japanese Utility Model Application Kokai No. 59-180435.
In recent years, however, there has been a dramatic reduction in the size of personal computers, as typified by notebook type personal computers, so that the extra space or volume required for the pivoting of a lever has already disappeared. Accordingly, an IC socket which is not equipped with a lever, and in which the slider is driven using a tool such as a screwdriver, etc., only when the IC package (such as a CPU, etc.) is replaced, has been proposed. For example, in Japanese Patent Application Kokoku No. 2-54632, a ZIF type IC socket (shown here in FIGS. 13 and 14) is disclosed in which the contact spring parts 142 of contacts 140 are caused to contact the leads (not shown in the figures) of the IC package by means of a tool 170 with a rectangular cross-sectional shape that is separate from the IC socket 110, as shown in FIG. 13. In order to cause the contact spring parts 142 of the contacts 140 to contact the leads of the IC package, the tip end of the tool 170 is first inserted into a substantially triangular tool insertion hole 152 formed in the slider 150 and an oppositely oriented substantially triangular tool insertion hole 134 (see FIG. 14) formed in the socket main body 130. Next, the slider 150 is caused to move in the direction indicated by arrow A (see FIG. 14) by turning the tool 170 in the clockwise direction. As a result of the movement of the slider 150, the spring contact p arts 142 of the contacts 140 accommodated inside the recesses 154 of the slider 150 are driven outward so that these spring contact parts 142 contact the leads of the IC package.
However, the socket main body 130 and slider 150 are generally made of plastic; accordingly, when the slider 150 is moved by turning the tool 170, one side edge portion 172 of the tool 170 bites into one side 152a of the substantially triangular tool insertion hole 152, so that there is a danger of indentation or damage, etc., occurring in this side 152a. As a result, the IC socket 110 cannot withstand numerous insertions and removals of IC packages, i. e., numerous movements of the slider 150.
Furthermore, the action point of the tool insertion hole 152 of the slider 150 that contacts the tool 170 is always in a position that contacts a corner (side edge portion 172) of the tool 170. As a result, the distance from the rotational fulcrum of the tool 170 is relatively large, so that the force required in order to rotate the tool 170 cannot be reduced.
Accordingly, one object of the present invention is to provide a compact ZIF type sock et which has the durability to withstand numerous movements of the slider.
Furthermore, another object of the present invention is to provide a ZIF type socket in which the force required in order to drive the tool is relatively small.
The ZIF type socket of the present invention is characterized by the fact that in a ZIF type socket which consists of a base housing that accommodates numerous contacts, and a slider that can move across said base housing, and in which the aforementioned slider is caused to move by inserting a plate-form tool into tool insertion holes formed in the aforementioned base housing and the aforementioned slider and rotating said tool, the action points of the aforementioned tool insertion holes contacted by the aforementioned tool are circular-arc-form projections.
It may be desirable that the members that have the circular-arc-form projections be metal members that are separate from the aforementioned base housing and slider, and that are respectively attached to the aforementioned base housing and slider.
Furthermore, the distance between the circular-arc-form projections on the side of the base housing and the circular-arc-form projections on the side of the slider may be shorter than the length of the long side of the tool.